Relay.



L. A. HAWKINS.

RELAY.

APPLICATION FILED NOV.18|1911.

1 1 52,088.. Patented Aug. .31, 1915.

'UNITED STATES OFFICE.

LAURENCE A. HAW'KINS, OF SCHENECTADY, NEW YORK, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO THE UNION SWITCH AND SIGNAL COMPANY, A CORPORATION OF PENN- SYLVANIA.

RELAY.

Application led November 18, 1911.

T0 all w71 0m, it may concern:

Be it known that I, LAURENCE A. HAW- KINS, a citizen of the United States, residing at Schenectady, in the county of Schenectady and State of New York, have invented certain new and useful Improvements in Relays, 'of which the following is a speciiication.

-My invention relates to alternating current relays, andparticularly to relays of this type which are selective as to frequency, that is, which are responsive to currentof one frequency and not to current of another frequency.

I will describe two forms of relay embodying inyinvention and then point out the novel features thereof in claims.

In the accompanying drawings, Figure l is a diagrammatic view showing one form of relay embodying my invention. Fig. 2 is a diagrammatic view showing another form of relay embodying my invention. Figs. 3 and lare vector diagrams representing the phase relations in the windings of the relays shown in Figs. 1 and 2 ,when supplied with currents of two frequencies.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. 1, I have here shown a relay of the well-known vane7 type, comprising as usual a magnetic core l0 between the polepieces of which moves a vane 11 of non-magnetic conducting material. The core 10 is as usual provided with a winding B which in the present invention is divided into three sections b', b and b2. Each of these sections is included in a separate branch, the three branches being connected in multiple and energized from a source of current E. Included in vthe branch circuit with section b2 is a con denser 5;' included in the branch with seetion b is a reactance 6; and included in the branch with section b is a non-inductive resistance 7, which resistance may, if desired, be included in the section b itself. It will be noted that section b is connected with the source E in the reverse direction to the other two sections.

The condenser, reactance and resistance may be so proportioned that with current of one frequency flowing in the three sections of the winding, the resultant magnetomotive force induced in the core l0 is substantially zero, while with current of a dif- Specication of Letters Patent.

Patented Aug. 31, 1915.

serial No. 660,998.

ferent frequency the resultant magnetomotive force is of considerable magnitude. For example the relay may be designed for use in a situation in which the normal operating current is cycles, and in which a source of stray current of 25 cycles exists. The conditions in the core 10 would then be substantially as indicated in the vector diagrams in Figs. 3 and 4. In Fig. 3, which indicates the conditions for 25 cycle current, o-E represents the voltage of the source of current E; o-J)2 represents the phase of the magnetomotive force produced in the core. by the current in section b2, this magnetomotive force being in-advance of the voltage because of the condenser 5; 0 7/ represents the phase of the magnetomotive force induced in tlie core bv the current in section b, this magnetomotive force lagging behind the voltage because of the reactance G; and 0 6 represents the phase of the magnetomotive force induced in the core by the current in section this magnetomotive force being at substantially 180o from the voltage because section Z) is connected reversely to the other two sections. It will be clear from the dash lines in this' diagram that the resultant of these three magnetomotive forces is Zero, hence no torque is exerted upon the vane 11. But when 60 cycle current flows in the winding, the conditions are substantially as indicated in Fig. 4. 0-62 is lengthened because a greater current of the higher frequency flows through the condenser 5;` o-b is shortened because a lesser current of the higher fre quencv flows through the reactance 6; and o-Z) remains approximately the same as in Fig. 3. The resultant of these three magnetomotive forces is OB, which' is of considerable magnitude, hence a torque will therefore be exerted upon the vane l1.

In Fig. 2 I have shown a two-winding relay embodying my invention, the particular relay here shown being of the induction mo'- ktor type and comprising as usual two windvings A and B and a rotor C which operates afteri explained. Winding B comprises three sections b, b and b2 connected in multiple and having in series respectivel therewith a resistance 7, a reactance 6 an a condenser 5, exactly as the winding B 1n Fig. l. The vector diagrams for Winding B on 25 and 60 cycle currents res ectlvely are as shown in Figs. 3 and 4, -B in Fig: 4 representing the resultant magnetomotive forceproduced by this winding on 60 cycle current. The magnetomotive force `produced by this winding on 25 cycle current is, of course, zero as indicated in Fig. 3. Since for maximum eiiiciency of operation of a relay of this type the angle between the magnetomotive forces produced by the two windings A and B is 90", the current supplied to winding A-is preferably 90 from the resultant magnetomotive force or current of Winding B, as represented by O--A in Fig. 4. As stated before, this current supplied to winding A is at 60 cycles, and it therefore co-acts with the 60 cycle current supplied to winding B to produce torque on the rotor C and thereby close contact I. Of course, if the supply of 60 cycle current to winding B is discontinued, the torque on motor C ceases, and contact 8 then opens by gravity. If, while the 60 cycle current is absent from winding B the 25 cycle current should flow in this winding, the magnetomotive force produced thereby would be substantially zero, as hereinbefore explained. and it would therefore'have no effect on the relay; or if the 25 cycle current in winding B should produce a small resultant magnetomotive force, it would not co-act with the magnetomotive force producedv by winding A to exert a torque on the rotor because these two magnetomotive forces would be at different frequencies.

In each of the relays shown in Figs. 1 and 2, the movable member 11 or C is provided with a circuit controlling member 8 which engages and disen ges with contacts 9 in the usual manner or the control of an electric circuit.

Although I have herein shown my invention applied to only two forms of relay, it

is understood that I do not limit myself to these'specic forms.

Relays embodying my invention are adapted for use for any purpose when a relay selective as to frequency is desirable. They are particularly adapted for use as track relays for railway signaling onv electric railways on which the propulsion current is alternating. In such cases, the frequency ofthe propulsion current is usually 25 cycles, and a signaling current Aof a higher frequency, usually SO'cycles, is applied to the track rails to control the track relays. When a relay of the type shown in Fig. 1 is used in such'a situation, its

winding B is energized from the 'track rails,

and the several branches including the sections of this Winding are so adjusted that when energized by current of the signalin frequency (G0 cycles in the case assumed the resultant magnetomotive force 1s of considerable vvalue so that the relay responds to this current by closing its contacts, but that when energized by current of the propulsion frequency (25 cycles in the case assumed) the resultant magnetomotive force is substantially Zero and the relay therefore does not respond-to this current to close its contacts.

When the relay shown in Fig. 2 is used in such a situation, the winding B is usually enerjgized from the track rails, and winding is energized from a source-of 60 cycle current distinct from the track rails. The branches for the.. three sections of winding B are adjusted as just explained for the winding B of the relay shown in Fig. 1, so that this winding produces a considerable magnetomotive force at 60 cycles but a substantially zero magnetomotivel force at 25 cycles.

I havelfound in practice that when 25 cycle current is employed for the propulsion energy on an electric railway, the frequency of this current sometimes falls to or nearly to 20 cycles, o'wing to poor regulationgat-the power plant. Since 60 cycles is the? third harmonic of 20 cycles, a relay of the usual two-winding type may be operated to close its contacts by 2O cycle current in one winding and 60 cycle current in the other, provided the phases are right. But when a twowinding relay embodying my invention is employed under such circumstances, the

magnetomotive force produced by 20 cycle .current in winding B is so small that it cannot co-act with the 60 cycle magnetomotive force produced by winding A to exert suicient torque on the rotor C to close contact 8. This is true regardless of what type of twowinding relay is employed. Hence it will be seen that under these circumstances a relay embodying my inv'ention is absolutely immune to false operation by propulsion current.

The relay shown in Fig. 2 when thus used `has the following advantages over that shown in Fig. 1.-First, the greater part of the energy required is supplied directly to the local winding A and only a small part through the comparativelyineflicient track circuit; second, protection against false clear indications caused by broken down insulation joints may be obtained byl the proper relative connections of adjacent track circuits with the source of signaling current, as is well understood in the art.

vAlthough I have herein shown relay windings embodying only one form and adjustment of my invention, it is understood that various changes and modifications may be 'liao made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is 1. In a relay, means for producing a magnetomotive force varying with the frequency of the current supplied to said means and having approximately zero value at one frequency anda comparativel high value at a second frequency, means or producing by alternating current a second magnetomotive force of said second frequency and of substantially constant eii'ective value,l and a movable element operated by the coaction of said magnetomotive forces.

2. In an electromagnetic. device, a winding comprising a plurality of sections connected in parallel circuits and producing superim' posed and opposing magnetomotive forces, and means included in said parallel circuits for so controlling the amounts and phases of e the currents in the said parallel circuits that the resultant magnetomotive force produced by said sections is of substantially zero value at one frequency and of a comparatively high value at another f uency.

3. An electromagnetic evice comprising a winding having three :sections connected in multiple, and producing superimposed magn etomotive forces, the branches for said sections including respectively resistance, re-

actance and capacity, said sections being so wound and connected that the magnetomotive force produced by the section associated with the resistance is in opposition to that produced by the other two sections, and said branches being so proportioned that when current of one frequency is sup lied to the winding the magnetomotive orce produced by the section havin resistance associated therewith is equal an opposite to the resultant of the magnetomotive forces produced by the other two sections, whereby when current of another frequency is supplied to said winding the magnetomotive force of the section having the vresistance associated therewith is not equal and opposite to the resultant of the magnetomotive forces produced by the other two sections.v

4. An electromagnetic device comprising a plurality of winding sections producng` superimposed and opposing magnetomotive forces and connected to the same source of current supply, the time constants of the circuits for said windings being different, whereby the relative strengths of the magnetomotive forces produced by said sections 

